Xanthan gum is a commercially important viscosifier produced by the fermentation of glucose, starch, or sucrose by strains of the bacteria Xanthomonas campestris. Production costs for xanthan gum are comparatively high and commercial applications could be greatly expanded if costs were reduced. A significant fraction of the production cost of xanthan gum is attributed to the raw material carbohydrate substrates. Therefore, it is desirable to develop methods to produce xanthan gum which use low-cost sugars or other substrates.
In our prior applications, Ser. Nos. 07/517,551 and 07/180,945, we have described an engineered strain of Xanthomonas campestris which is able to utilize lactose as a substrate and provide a high productivity of high quality xanthan gum product. As shown therein, this strain effectively utilizes relatively pure lactose, or whey as a substrate.
In the dairy industry, efforts are made to recover as much of the usable protein and other organic values as possible. For this purpose, the whey or milk is filtered and the recovered solids, which include the predominant portion of the protein and other non-lactose values, are used for commercial purposes and products. The remainder, i.e., the filtrate or permeate as it is sometimes called, is usually considered to be a waste. Processes have been developed to remove some of the lactose from the permeate. The resulting waste stream from the processing of permeate, known as "Low Lactose Permeate", or "LLP", has less value than does the unfractionated permeate.
A problem that has been encountered in the use of whey for the production of xanthan gum using presently available commercial processes, is that the xanthan product obtained is of poor quality, i.e., low viscosity.